On 20 August 1929, off the coast of New Jersey, a biplane hooked itself to the bottom of a dirigible
and was carried along by the larger craft. This is the 2nd such
incident. The “snapon, snapoff” experiment is accomplished by the Navy
airship USS Los Angeles,
under Lt. Com. Herbert Wiley, and a Navy biplane. The biplane,
regulating its speed to that of the dirigible, flew close under the Los
Angeles. A large hook had been attached to the middle of the top wing of
the biplane, and from the bottom of the Los Angeles hung a U-shaped
yoke. Maneuvering the ship under the dirigible, the plane pilot slipped
the hook into the Los Angeles’ yoke and for 3 or 4 minutes the dirigible
carried the biplane. The plane pilot, by a cord arrangement in his
cabin, withdrew the hook from the yoke and flew clear of the dirigible.

Although designed as a pursuit plane or fighter, the Sparrowhawk's primary duty in service was reconnaissance,
enabling the airships it served to search a much wider area of ocean.
The Sparrowhawk was primarily chosen for service aboard the large
rigid-framed airships Akron and Macon because of its small
size (20.2 ft (6.2 m) long and with only a 25.5 ft (7.8 m) wingspan),
though its weight, handling and range characteristics, and also downward
visibility from the cockpit, were not ideal for its reconnaissance
role.
The theoretical maximum capacity of the airships' hangar was five
aircraft, one in each hangar bay and one stored on the trapeze but, in
the Akron, two structural girders obstructed the after two hangar bays, limiting her to a maximum complement of three Sparrowhawks. A modification to remove this limitation was pending at the time of the airship's loss. Macon had no such limitation and she routinely carried four airplanes.To achieve launching and recovery from the airship in flight, a
'skyhook' system was developed. The Sparrowhawk had a hook mounted above
its top wing that attached to the cross-bar of a trapeze mounted on the
carrier airship. For launching, the biplane's hook was engaged on the
trapeze inside the airship's (internal) hangar, the trapeze was lowered
clear of the hull into the (moving) airship's slipstream and, engine
running, the Sparrowhawk would then disengage its hook and fall away
from the airship. For recovery, the biplane would fly underneath its
mother ship, until beneath the trapeze, climb up from below, and hook
onto the cross-bar. The width of the trapeze cross-bar allowed a certain
lateral lee-way in approach, the biplane's hook mounting had a guide
rail to provide protection for the turning propeller (see photo), and
engagement of the hook was automatic on positive contact between hook
and trapeze. More than one attempt might have to be made before a
successful engagement was achieved, for example in gusty conditions.
Once the Sparrowhawk was securely caught, it could then be hoisted by
the trapeze back within the airship's hull, the engine being cut as it
passed the hangar door. Although seemingly a tricky maneuver, pilots
soon learned the technique and it was described as being much easier
than landing on a moving, pitching and rolling aircraft carrier.
Almost inevitably, the pilots soon acquired the epithet "The men on the
Flying Trapeze" and their aircraft were decorated with appropriate unit
emblems.Once the system was fully developed, in order to increase their
scouting endurance while the airship was on over-water operations, the
Sparrowhawks would have their landing gear removed and replaced by a
fuel tank. When the airship was returning to base, the biplanes' landing
gear would be replaced so that they could land independently again.For much of their service with the airships, the Sparrowhawks'
effectiveness was greatly hampered by their poor radio equipment, and
they were effectively limited to remaining within sight of the airship.
However, in 1934 new direction-finding sets and new voice radios were
fitted which allowed operations beyond visual range, exploiting the
extended range offered by the belly fuel tanks and allowing the more
vulnerable mother ship to stay clear of trouble.One interesting use of the Sparrowhawks was to act as 'flying
ballast'. The airship could take off with additional ballast or fuel
aboard instead of its airplanes. Once the airship was cruising, the
aircraft would be flown aboard, the additional weight being supported by
dynamic lift until the airship lightened.

Only one intact Sparrowhawk survives today. BuAernumber 9056 was pending write-off at NAS Hampton Roads in 1939 when it was transferred to the Smithsonian Institution. In later years it had been rebuilt, using parts from the surviving F9C-2 (BuAernumber 9057) and the XF9C-2 (9264). It was previously at the National Museum of Naval Aviation, at NAS Pensacola, and is currently displayed at the Steven F. Udvar-Hazy Center of the Smithsonian's National Air and Space Museum collection, wearing the markings of F9C-2 A9056 of USS Macon.

The cockpit of one of the Macon's Sparrowhawk's, photographed in 2006. The ribs of the upper wing. and the pilot's telescopic gunsight can be seen.

The remains of a further four aircraft lie at the underwater wreck-site of the Macon; the aircraft were found in their hangar when the wreck was discovered and documented in 1990 and 1991. These are known to have been BuAernumber 9058 - 9060.